Lately, there has been a trend in sustaining cities with food that was grown within a 100 mile radius. This is called the local food movement, which was created in response to the practice of importing food from other states and even countries, resulting in unsustainable land use practices, loss of biodiversity, and contributing to pollution when transporting. It has been posited that the new face of sustainable agriculture is growing the food supply within a 100 mile radius, stating that it is better for the environment. A group of researchers wanted to see how practical this would be, by mapping out the land available for growing crops in the Philadelphia area.
GIS applications were fundamental in conducting the experiment. First, the local food system was mapped. Data on the locations of farmers markets was collected. While it was found that over 50% of community gardens were in low-income areas, the food was mostly sold in areas with middle to high incomes. A food desert map was created to show this discrepancy by geocoding in ArcGIS, based on an ESRI dataset they downloaded. They measured how far away certain areas were from farmer's markets by using ArcGIS' network analysis tool. Maps were further refined to study the habits of local farmers and where they went.
Then, the researchers calculated the yield potential of Philadelphia. Any area, including lawns, that were grassy were considered fair game for growing crops. The researchers took a map of Philadelphia and broke its components into class polygons, with grassy areas representing one class. Using ArcGIS 10, they overlaid the zoning data they received and removed buildings in layers until only grassy areas were left so they could study them better.
They calculated the areas of grassy polygons to find growing potential. Using NDVI analysis, they found that 46% of the city's area could be developed for agriculture, not taking into account aesthetics and future growth. As for their map of the local food system, they found that currently it mostly catered toward middle and upper class incomes, which actually hindered the potential of it being sustainable as not all people have access to it.
Kremer, P., & DeLiberty, T. L. (2011). Local food practices and growing potential: Mapping the case of Philadelphia. Applied Geography, 31(4), 1252-1261.
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